Douglas 152L2 - Won't Start

[chrisbwy]

Hi All,

Here's hoping somebody knows why my scooter won't start.

About 18 months ago she ran fine, just before my father-in-law died. He rode it briefly up and down the drive. Prior to that the scoot was last taxed in 1992.

My plan was to re-tax and insure and ride, but loosing the chief mechanic set me back a lot. So the Vespa laid untouched for well over a year. Now she won't start.

Here's what I've tried...

1. new fuel fed from a plastic bottle direct to carb so as to bypass the old fuel in the tank.

2. carb dismantelled and cleaned out several times. Fuel is reaching carb.

3. damp start sprayed directly in the carb (where air filter would connect) and she fires up for a few seconds, sounds ok.

4. took the head off, new spark plug and decoked as best I could.

But for some reason it looks like the petroil mixture is not being pulled through the carb and into the engine. The plug remains dry.

A friend has mentioned crankshaft oil seal needs replacing, she's loosing compression.

Is this the most likely problem or something else? What checks can I do?

Thanks in advance,

Regards

Chris

[vespabromo]

Check your gear oil. If its very thin and smells of petrol, then you know your clutch side seal has gone.

[chrisbwy]

Will do, thanks.

Will this cause a drop in compression and an un-willingness to "pull" the petroil mixture through?

Is this an engine out job to replace?

[alan34]

Hello could also be the piston rings stuck in the grooves of piston and not pushing out onto cyclinder. if plug is dry.try push piston almost to top and squirt some wd40 in leave overnight kick over with rag over plug hole to catch excess try again squirting easystart in as you kick over.let us know how you get on cheers alan.

[alan34]

Hello also check spark plug is fireing has been stood a long time points might be sticking together.good luck.

[chrisbwy]

Thanks Alan, I was thinking about the rings. When I decoked the engine I only took the head off and cleaned the faces etc. not the rings.

I feel it is a simple problem and fingers crossed not a seal replacement.

Spark plug out and resting on head and it sparks fine. New plug.

I'll try as you suggest re rings and report back soon.

Cheers Chris

[vespabromo]

Also it would be a good idea to check your fuel pipe. It could be perished and have a kink in it. Check the fuel tap as well. The older style fuel taps have a bowl on them, they can get full of crud.

[chrisbwy]

Thanks, but I'm using a separate new fuel bottle hung from the handle bar direct to the carb.

Chris

[chrisbwy]

Hi All,

Yes I know it's been a few weeks but I've had a few other projects taking priority.

My vintage douglas 152L2 Vespa still won't start.

Latest things tried...

1. barrel off to find top ring stuck in, years of old fuel I suspect. Both rings out, cleaned up, now nice and free.

2. the carb is an Amal 503/1 - unique to this model I believe. Pilot jet out and cleaned, pilot air screw out, carb cleaner squirted in and I can see it exiting into the venturi. Pilot air screw back in fully, then out 1.5 turns as recommended elsewhere.

3. plug is still sparking strongly. But is dry, no fuel mixture is reaching the plug.

4. fuel tank and tap bypassed using separate fuel bottle, hung from handle bar direct carb. Fresh fuel. Remove the top of the float chamber and fuel is there.

5. spray damp start into the carb directly and she fires for a second or two.

So what's stopping the scooter starting?

A friend has suggested she's down on compression, maybe due to leaking crankcase oil seals. Plug out and finger over the hole and I can feel lots of compression, but not measured it.

Does this 152L2 engine have crankcase oil seals and could that be the issue? If yes - how easy are they to change? Can a check be done to make sure the seals are at fault first?

Could there be something else I have missed?

Does the carb need priming somehow?

Any help or ideas much appreciated - I really want this nice vintage vespa out on the road!!!!

Regards and thanks

Chris

[chrisbwy]

I have stripped and cleaned out the carb many times.

Took it apart tonight whilst full of fuel to see how far through the carb the fuel was getting. The float chamber is half full and the fuel is reaching the main and pilot jet chamber ok.

It's driving me crazy why the fuel mixture isn't being "pulled" through the pilot jet. The pilot air screw has been out and carb cleaner squirted through. Likewise the brass pilot jet has been out, carb cleaner through the hole and jet.

Should I measure the compression and if so, what psi reading would you expect?

Cheers all, Chris

[alan34]

Chris scoot has been stood a long time crank sealsprobebly shot try putting some petrol and oil in stray bottle and ignition on choke on spray into air intake while kicking over if it fires keep revs up a bit while spraying into carb if warmed up a bit it might run on own.or put a drill on flywheel and spin it over seen it on youtube starting old vespa let us know how you get on cheers alan.

[chrisbwy]

Thanks Alan34.

I've started a new thread on the subject of crankcase seals to aid my knowledge.

I will investigate them.

I'm in the process of getting a compression tester to aid checking.

Best wishes

Chris